| Protein S is a vitamin K-dependent, potent neutral anticoagulant plasma glycoprotein. Protein S has a molecular weight of approximately 70kD and concists of a single polypeptide chain. The concentration of protein S in human plasma is 25ug/ml, with a half-life of approximately two days. About 40% of Protein S in plasma is in a free form, whereas 60% is complexed with C4b-binding Protein (C4BP). Only the free Protein S functions as a cofactor to antigen presenting cells (APC) in the APC-dependent degradation of Factor Va and Factor VIIIa. |
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| Catalog # | P9108-09 |
| Protein S is thought to function in both the coagulation and complement cascades. It has been suggested that g-carboxyglutamic acid (gla) dependent binding of protein S to negatively charged phospholipids may function to concentrate C4BP at cell surfaces following injury. |
| In the coagulation system, Protein S functions as an anticoagulant cofactor protein. Activated Protein C (APC) forms a 1 | 1 stoichiometric complex with Protein S in the presence of Ca2+ and phospholipid vesicles (Kd=6x10e-9M). In the presence of Protein S, a moderate increase (3-10 fold) in the rate of factor Va and factor VIIIa inactivation by APC is observed in plasma and on the surface of unstimulated platelets. Protein S bound to C4BP does not possess APC cofactor activity. Recently, an additional binding protein which enhances the activity of Protein S has been described. Proteolytic inactivation of Protein S by thrombin has been proposed as a regulatory mechanism in this system. A single cleavage by thrombin abolishes Protein S cofactor activity by removing an NH2-terminal peptide (Mr=8000) which contains the gla domain. |
| The domain structure of Protein S is similar to that of the other vitamin K-dependent coagulation factors with the exception that Protein S does not possess the catalytic triad. Protein S is a single chain protein containing 10 gla residues in the NH2-terminal domain and 4 epidermal growth factor (EGF) domains. |
| Applications | Suitable for use in Immunoelectrophoresisas and ELISA for Protein S. Other applications not tested. |
| Recommended Dilution | ELISA: capture |
| Optimal dilutions to be determined by the researcher. |
| Storage and Stability | May be stored at 4°C for short-term only. For long-term storage, store at -20°C. Aliquots are stable for at least 12 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. |
| CAS Number | n/a |
| Clone Type | Polyclonal |
| Isotype | IgG |
| Host | Sheep |
| Source | Human |
| Concentration | ~2mg/ml |
| Form | Supplied as a liquid in 0.01M HEPES, pH 7.4, 0.15M sodium chloride and 50% glycerol. No preservatives are added. |
| Purity | Purified by immunoaffinity chromatography. |
| Immunogen | Human Protein S (PS) purified from plasma. |
| Specificity | Specific for human Protein S. |
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| Important Note | This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological. |
